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Linked Duplicates
https://docs.blender.org/manual/en/dev/editors/3dview/object/editing/duplication.html?highlight=duplicate%20instances

Mode:   Object Mode
Panel:  Tool Shelf ‣ Tools ‣ Edit ‣ Duplicate Linked
Menu:   Object ‣ Duplicate Linked
Hotkey: Alt+D  

You also have the choice of creating a Linked Duplicate rather than a Duplicate; this is called a deep link. This will create a new object with all of its data linked to the original object. If you modify one of the linked objects in Edit Mode, all linked copies are modified. Transform properties (object data-blocks) still remain copies, not links, so you still can rotate, scale, and move freely without affecting the other copies. Reference Expl. Duplicate Example for the discussions below.

Note
If you require the applied material to not be linked you will need to turn on "Object" data on the material panel here.